“Actually, it can. Food needs moisture in the air for mold to form," according to the restaurant. "Without it, food will simply dry out – sort of like bread left out on a counter overnight to make croutons for stuffing. You might have seen experiments which seem to show no decomposition in our food. Most likely, this is because the food has dehydrated before any visible deterioration could occur."

A number of experiments have subjected McDonald’s and other fast food to decay tests as well. Buzzfeed placed burgers from McDonald’s, Burger King, Carl’s Jr. Wendy’s, Umami burger, In-n-Out and Jack in the Box in a glass jar for 30 days and examined them for decay.

Serious Eats conducted an exhaustive experiment comparing multiple aspects, including patty size and bun, of McDonald’s burger with a homemade version. They found that even a homemade burger made of similar proportions will not decay in a temperature-stable and moisture-controlled environment.